The Berkeley/Stanford Children's Environmental Health will investigate the role of air pollution in children's health, in particular, effects on birth outcomes, birth defects, asthma, obesity, and the immune system. Sonoma Technology Inc.'s (STI) role in the study will be to perform exposure assessment as part of the Center's Exposure Core. We will collect ambient polycyclic aromatic hydrocarbon and black carbon air pollution data in Fresno and developed refined estimates of the subject's exposure for various time periods of their lives through data analysis and modeling. STI's work consists of four main tasks: characterize historical air quality in the SJV; collect PAH and black carbon data at existing stations in Fresno; conduct saturation sampling campaigns; and conduct exposure data management, analysis, and modeling All exposure data from the study will be quality assured and compiled into a common database for use by all investigators. The historical and current air quality data will be used to assign historical exposures for relevant time periods in the subjects lives. The current air quality and meteorological data will be used with dispersion model estimates and traffic, land-use, geophysical, and demographic data to develop spatiotemporal models of daily PAH concentrations. The development of spatiotemporal models will be conducted jointly with UCB staff. In addition, where sufficient data justify the approach, STI will apply microenvironmental modeling techniques to estimate the personal exposure levels of subjects in the study. STI will document our methods and results, and work with UCB staff on the preparation of project specific papers and interpretation of scientific results. Fred Lurmann, the STI PI, will participate in regular Exposure Core and Center meetings.